Effect of Powder Flow Rate on Surface Finish in Laser Additive Manufacturing Process

Laser metal deposition process is an additive manufacturing process that can produce three-dimensional part through material addition. It that belongs to the class of directed energy deposition. This technology is still fairly new and some of the physics of the process is not fully understood. In this study, the influence of the processing parameter, namely: the powder flow rate, on the resulting physical property of laser metal deposited titanium alloy powder on titanium alloy substrate was carefully investigated. The powder flow rate was varied between 1.44 g/min and 7.2 g/min while the laser power, the gas flow rate, the laser spot size and the scanning speed were maintained at constant values of 3 kW, 2 l/min, 2mm and 0.004 m/s respectively. The laser metal deposition experiment was conducted using a 4.0 kW Nd: YAG laser. The surface roughness was measured using Jenoptik surface analyzer. The results showed that the surface roughness increases when the powder flow rate was increased. The minimum average surface roughness value of 4.5 μm was achieved at the lowest powder flow rate of 1.44 g/min. The low roughness value obtained at lower powder flow rate could be attributed to proper melting of the powder at these settings.